books.google.comhttp://books.google.com/books/about/A_Key_to_the_Exercises_in_Ollendorff_s_N.html?id=4FQBAAAAYAAJ&q=viel+Uhr&utm_source=gb-gplus-shareA Key to the Exercises in Ollendorff's New Method of Learning to Read, Write, and Speak the German Language